In conjunction with the diagnosis and treatment of certain cardiac conditions, various types of hemodynamic information may be acquired to determine how effectively the patient's heart is functioning. For example, a cardiac monitoring system may acquire information relating to oxygen saturation, blood pressure, cardiac output, and other parameters. Under some circumstances, a determination of cardiac output (e.g., the amount of blood pumped by the heart per minute) may be a particularly useful measure of how effectively the heart is working.
Cardiac output (“CO”) for a patient may be estimated through the use of the Fick equation:
                    CO        =                                            VO              2                                                      (                                                      SaO                    2                                    -                                      SvO                    2                                                  )                            ·              1.34              ·              Hb              ·              1000                                ⁢                      (                          liters              /              minute                        )                                              EQUATION        ⁢                                  ⁢        1            
Here, {dot over (V)}O2 relates to the patient's oxygen consumption, SaO2 relates to the patient's arterial oxygen saturation, SvO2 relates to the patient's venous oxygen saturation, and Hb relates to the total hemoglobin in the patient's blood.